1. Field of the Invention
The present invention relates to an endoscope in which an insertion unit rotates in relation to an operation unit.
2. Description of the Related Art
An endoscope comprises an elongated insertion unit which is inserted into a body cavity of a patient, and an operation unit connected to a proximal end part of the insertion unit by which the endoscope including the insertion unit is operated. A different type of endoscope from that described above comprises an elongated insertion unit inserted into a body cavity of a patient, and an operation unit by which the endoscope including the insertion unit is operated, wherein the operation unit is connected to a proximal end part of the insertion unit with the insertion unit maintained rotatable axially about a lengthwise direction of the insertion unit.
For example, Jpn. Pat. Appln. KOKAI Publication No. 2004-305413 discloses an endoscope as described above.
In the Publication No. 2004-305413, a mouthpiece of an insertion unit is provided at a proximal end part of the insertion unit, and a mouthpiece of an operation unit provided at a distal end part of the operation unit. In order to connect the insertion unit and the operation unit to each other, the mouthpiece of the insertion unit is engaged in the mouthpiece of the operation unit. Therefore, the mouthpiece of the insertion unit and the mouthpiece of the operation unit function as a connection unit which connects the insertion unit and the operation unit together.
This endoscope comprises a first O-ring that ensures water-tightness of the operation unit, and a second O-ring which seals the insertion unit and the operation unit to be water-tight with respect to each other. The first O-ring is provided between the distal end part of the operation unit and the mouthpiece of the operation unit. The second O-ring is provided at a connection unit, more specifically between the mouthpiece of the insertion unit and the mouthpiece of the operation unit. When the insertion unit rotates in relation to the operation unit, the second O-ring applies frictional resistance to the insertion unit and thereby controls resistive torque during the rotation. Thus, the second O-ring serves as a sealing member by which the insertion unit and operation unit are sealed water-tight, and also as a frictional resistance member which applies frictional resistance.